virtualbox.org

I've got three CentOS 5.3 guests (x86_64) on a Ubuntu 9.10 (x86_64) which are in a cluster.
I've created a new vdi file to simulate a SAN to share it between all nodes of my cluster, to create a GFS volume, and I've assigned it to all my guests.
When I start the first one, everything is ok, but when I start the second one, I obtein this message :

"Medium '/home/fred/.VirtualBox/HardDisks/GFS1.vdi' is locked for writing by another task."

Is it possible to share a vdi file to create a cluster ?
I've found nothing about this on virtualbox website and on google.
Any idea ?

Can you setup one of the VMs as an iSCSI server, or setup another VM or even a real machine as an iSCSI server, then configure the VMs as iSCSI initiators?
(VirtualBox has built-in iSCSI support, see section 5.5 of the user manual.)

VirtualBox will not allow more than 1 running VM to use a VDI file, unless they have snapshots over that VDI, which then means they all have their own fork of the disk contents rather than sharing the same current disk: not what you want.